Collection and Characterization of Phloem Exudate from Strawberry Pedicels

Abstract

Fruit of strawberry ( Fragaria ×ananassa Duch. ‘Brighton’) were removed, and pedicels attached to plants were placed in ethylenediaminetetraacetate (EDTA) to collect phloem sap. The rate of sugar exudation increased with the size of the fruit, but was lower than the rate of dry matter accumulation of the fruit at the time of its removal. When plants were fed 14 CO 2 , radioactivity appeared in the phloem sap after 3 hr, and the rate of exudation of labeled assimilate was maintained at a fairly constant rate for 6 hr. About 92% of the radioactivity in the exudate was in the sucrose fraction, with the remaining in glucose (2%), fructose (1%), and acidic and basic fractions (4%). The results indicate that sucrose is the major assimilate translocated to the fruit.